Method of making seamless tubular bell section

ABSTRACT

A musical instrument such as a trumpet has a seamless tubular bell section of solid brass and uniform thickness. Such bell section is made from a section of brass tubing of uniform wall thickness and diameter which is initially drawn to progressively taper its wall thickness along its length while maintaining the uniformity of its outside diameter. The end with the greater wall thickness, which is the future flared bell, is enlarged, and the non-enlarged portion of the blank is progressively reduced to a form having a tapered inside diameter which merges with the enlarged end portion. The enlarged end portion is expanded by means of internal hydraulic pressure, after which excess material is trimmed off and the workpiece is finished in a customary manner.

United States Patent 1 1 ,871,094 Nichols 1 1 Mar. 18, 1975 METHOD OFMAKING SEAMLESS TUBULAR BELL SECTION [75] Inventor: William Lee Nichols,Brea, Calif.

[73] Assignee: Norlin Music, Inc., Lincolnwood, Ill.

[22] Filed: Apr. 26, 1974 [21] Appl. No.: 464,305

[52] US. Cl 29/l69.5, 29/D1G. 11, 29/D1G. 41, 29/421 R, 72/275, 72/283,72/62, 84/387 {51] Int. Cl. B29d 17/00 [58] Field of Search.....29/l69.5, D16. 11, DIG. 41, 29/421 R, 161; 84/387; 72/275, 283, 370, 62

[56] References Cited UNITED STATES PATENTS 1,740,144 12/1929 Barrett29/421 1,764,561 6/1930 Gulick 29/421 1,826,077 10/1931 Johnson 29/l69.52,886,170 5/1959 Kerr 72/283 2,998,125 3/1961 Hahn et al. 72/283 X3,327,513 6/1967 Hinshaw 72/283 X 3,735,463 5/1973 Merola 29/D1G. 11 XPrimary E.\'aminer-C. W. Lanham Assistant E.raminerVictor A. DiPalmaAttorney, Agent, or Firm-Hill, Gross, Simpson, Van Santen, Steadman,Chiara & Simpson 57 I ABSTRACT A musical instrument such as a trumpethas a seamless tubular bell section of solid brass and uniformthickness. Such bell section is made from a section of brass tubing ofuniform wall thickness and diameter which is initially drawn toprogressively taper its wall thickness along its length whilemaintaining the uniformity of its outside diameter. The end with thegreater wall thickness, which is the future flared bell, is enlarged,and the non-enlarged portion of the blank is progressively reduced to aform having a tapered inside diameter which merges with the enlarged endportion. The enlarged end portion is expanded by means of internalhydraulic pressure, after which excess material is trimmed off and theworkpiece is finished in a customary manner.

16 Claims, 20 Drawing Figures sum 3 n; s

PATENTEB HAR I 8 I975 PATEHTEUHAMWEJ O SHEETS 5 3 871.0q4

METHOD OF MAKING SEAMLESS TUBULAR BELL SECTION BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to musicalinstruments, and more particularly to the construction and method ofmanufacturing a tubular bell section thereof.

2. Prior Art Heretofore, it has been most common to manufacture a bellsection of a brass instrument by beginning with sheet metal, blankingthe same appropriately, forming it and joining the edges such as bymeans of brazing to form a tubular component. The discriminatingobserver can usually find the longitudinal seam that runs the length ofsuch bell section. In some forms of the prior art, the flared bellportion has been joined to a tubular portion by means of a seam runningcircumferentially about the instrument a few inches from the bell.

Apart from any objection based on aesthetics that such seams may create,which are particularly noticeable when an instrument is not plated,there are sophisticated musicians who object to the existence of suchtype of construction, contending that the tonal quality is notquiteideal. From the manufacturing standpoint there are also seriousobjections. When a seam is created as by brazing it must thereafter bepolished and buffed so as to provide a good continuity or smoothness offinish as possible. The labor of doing this work is not onlyobjectionable per se, but extremely skilled craftsmen must be employedto complete this delicate finishing since the metal is only a fewthousandths of an inch thick in the first instance. The inherent joiningprocess does not provide continuity of thickness, and therefore therewill .be thicker and thinner spots along such seams, and even the bestcraftsman will at times in scraping and polishing the seam, breakthrough the weld or heat-type bond, leaving a small hole. Now it isobvious that customers do not want to buy horns that have a small holein the side of the bell, and therefore such a workpiece becomes scrapor, as a minimum, must be reworked at some expense going back to themethod by which the heat-bond was created. Brazing is not particularlyidea] where the horn is not to be plated, and there the brass edges ofthe sheet itself must be melted so asto provide a constant coloringeffect, but working with materials that are only a few thousandths of aninch thick to fuse the edges thereof together requires great skill tominimize the problems mentioned above. Even when an ideal seam has beenmade, as a practical matter, there are still discontinuities inthickness compared to the thickness of the original sheet metal.

SUMMARY OF THE INVENTION According to my invention, there is provided aseamless tubular bell section of solid brass and of uniform thickness.This article is made by beginning with a blank of brass tubing ofuniform wall thickness and diameter, drawing the blank to progressivelytaper its wall thickness along its length while maintaining uniformityof its outside diameter, thereafter enlarging the end section of theblank having the greater wall thickness and reducing the diameter of thenon-enlarged portion of the blank to provide a taper that merges withthe enlarged end portion, the final flare of the bell being produced bymeans of internally applied hydraulic pressure.

Accordingly, it is an object of the invention to provide a seamlesstubular bell section of solid brass.

Another object of the present invention is to provide a bell section ofuniform thickness without any discontinuities in thickness byelimination of thermal bonds. A furtherobject of the prevent inventionis to provide a method for making a seamless tubular bell section ofsolid brass.

A still further object of the present invention is to eliminate themanufacturing difficulties inherent in employment of a constructionhaving a thermal seam.

Another important object of the present invention is to provide a methodfor making an instrument bell for producing superb tonal qualities.

Many other advantages, features and additional objects of the presentinvention will become manifest to those versed in the art upon makingreference to the detailed description and the accompanying drawings inwhich a preferred structural embodiment incorporating the principles ofthe present invention is shown by way of illustrative example.

ON THE DRAWINGS FIG. 1 shows the tubular workpiece, partially insection, receiving an initial necking operation;

FIGS. 2 and 3 show successive drawing operations which employ a taperedmandrel;

FIGS. 4 and 5 show successive drawing operations using expansionmandrels;

FIGS. 6-10 illustrate seven successive drawing operations by which thediameter of the non-enlarged portion is reduced;

FIGS. 11 and 12 illustrate successive drawing operations of the same endemploying steel washers as drawing dies along with tapered mandrels;

FIG. 13 illustrates a further sizing operation performed by a die on theenlarged end, if necessary;

FIGS. 14-17 illustrate four successive hydraulic forming operations;

FIG. 18 illustrates the workpiece as formed but with surplus materialremoved;

FIG. 19 illustrates the workpiece after the periphery of the bell hasbeen flattened; and

FIG. 20 illustrates the bell section after the same has been finished.

AS SHOWN ON THE DRAWINGS The principles of the present invention areparticularly useful when embodied in a musical instrument which, asshown in FIG. 20, includes a seamless tubular bell section of solidbrass and of uniform thickness, generally indicated by the numeral 21.

The bell section 21, according to the invention, is made from a blank ofbrass tubing of uniform wall thickness and diameter. Any of the knownbrasses of the lead-free type is suitable. To the extent feasible, thedrawings have been made to scale, the initial blank 22 having a typicallength of 15 inches, a diameter of 1.70 inches, and a uniform wallthickness of 0.055 inch. After the blank has been deburred, the blank 22is installed in a press illustrated diagrammatically by force arrows 23by which the blank 22 is urged against a necking tool 24 to form aslight flange or neck as shown in FIG. 2 at 25. A tapered mandrel 26 isinserted in the blank 22 and is limited by the neck 25. Force is thenapplied to the mandrel 26 forcing it with the blank 22 through a firstdrawing die 27 which has a tapered leadin surface. The right end of themandrel 26 is smaller than the left end by about 0.07 inch, so that asthe drawing operation continues, the wall thickness is taperedprogressively thinner at the left end while the outside diameter ismaintained. This operation increases the length of the blank by morethan 6 inches.

After annealing, if necessary, the mandrel 26 is used once more with theblank 22 to pass it through a ring die 28 of lesser diameter, therebyfurther increasing the length of the blank and further reducing the wallthickness while maintaining a new smaller outside diameter. Thisoperation increases the length of the blank by more than 7 inches, andthe blank is then trimmed to a desired length with stock being removedfrom both ends so as to eliminate the necking 25. The workpiece is thendeburred and the thicker right end thereof is annealed and, as shown inFIG. 4, an expansion mandrel 29 having a tapered entrant end is forced,as by a press, into the workpiece to radially draw its shape from thatshown in solid lines in FIG. 4 to that shown in FIG. 5.

Following any necessary annealing, a larger expansion mandrel 30 isforced into the end as shown in FIG. to change the shape of theworkpiece from that shown in FIG. 5 to that shown in FIG. 6. As shown,the expansion mandrels 29,30 have a cylindrical configuration, but thisis not critical.

During use of the expansion mandrels 29, 30, the nonenlarged portion 220is externally supported by a rigid sleeve 31 having a tapered end 32which is substantially parallel to the tapered ends of the mandrels 29,to assist in providing a transition zone between the enlarged endportion 22b and the remainder 22a of the workpiece 22. The enlargedportion 22b of the workpiece now has the desired diameter. If for anyreason its diameter is excessive, or if the enlarged portion 22b shouldbecome excessive, an optional clean-up step shown in FIG. 13 anddescribed below could be employed as a final sizing step. However, Ihave found that this step is normally not necessary.

The expansion mandrel 30 is removed and in place thereof, a mandrel 33shown in FIG. 6 is inserted, it having a plug portion 33a of slightlysmaller diameter than the enlarged portion 22b of the workpiece, and anelongated guide portion 3311 which extends through the region of lesserbore with a rather loose fit, the same serving merely as a guide toprevent permanent bowing of the workpiece as it is pressed through areducing die 34 to reduce the outside diameter uniformly up to theexternally tapered portion 220.

The operation is repeated, using the same mandrel, but a smaller die 35shown in FIG. 7. A mandrel having a smaller guide portion is thensubstituted and the workpiece is then passed through a further die 36 ofreduced diameter. Using the same mandrel 37, the workpiece is passedthrough a further drawing die 38 of lesser diameter as shown in FIG. 8at the end of the operation. A mandrel of a smaller diameter guideportion is then used in passing the workpiece 22 through a furtherdrawing die 39 of reduced diameter, and the same mandrel 40 is used topass the workpiece 22 through a still further drawing die 41 of reduceddiameter, for example, about a 0.95 inch diameter.

As then shown in broken lines in FIG. 9, the workpiece is trimmed to adesired length and the small end thereof is subjected to a swagingoperation by means of a tapered swaging tool 42 which is rotatablydriven as the workpiece is pressed thereagainst, the mandrel 40 havingbeen removed.

As shown in FIG. 10, a plug 43 is installed in the tapered end andtension, indicated by an arrow 44, is applied to the small end of theworkpiece to draw it through a further die 45 of lesser diameter, forexample, about 0.84 inches over a length about 6 inches long.

The tip is then annealed and, as shown in FIG. 11, is put intoengagement with a further swaging tool 46 after which a plug 47 isinserted, and tension is applied thereto to pull the portion oftheworkpiece that is remote from the enlarged end through a further die.As shown in FIG. 11, a die support 48 is provided with a clearanceopening which could be as large as the enlarged end, but is hereillustrated as being one that blocks the tapered portion 220. The actualdie begins as a steel washer 49 having a central opening just largeenough to receive the workpiece, for example, about 0.59 inch. The steelwasher 49 beings in flat form and as the drawing operation proceeds, thewasher flares out progressively as shown in FIG. 11 and is thendiscarded. During this operation, as the workpiece is pulled through thedie 49, there is present inside the workpiece, a tapered mandrel 50which has a configuration along the portion of the workpiece wiped bythe die 49 which generally approximates the finished inside dimensiondesired for the particular instrument. The mandrel 50 is thus taperedwith an exponential contour conforming to that desired for a particularmusical instrument.

The tip is once more swaged as by a tool 51 shown in FIG. 12 and a plug52 is inserted therein and tension is applied thereto to draw thereduced end of the workpiece through a further steel washer 53 held by asupport 54, there being a precision exponentially contoured taperedmandrel 55 therein which has the precise internal dimension desired forthe finished bell section. The steel washer dies 49 and 53 also begin toremove some of the discontinuities that appear in the region 220 asshown in prior views, as shown in FIG. 13. If it is desired to resizethe outside diameter of the enlarged portion, such resizing could bedone at this time, for example, by means of a die 56 which isnormallynot necessary. The workpiece 22 is now nearly ready to be installed in aspecial forming fixture diagrammatically shown in each of FIGS. 14-17.

The forming operations are conducted with a special hydraulic fixturewhich includes an external support portion 57 which is sized to act onthe outside of the workpiece with a close fit along the region that hasbeen properly sized, but the variations that exist in practice in theportion 22c cause successive workpieces to take slightly differentpositions along the support portion 57. Therefore, the workpiece isgauged and is trimmed off at the small end, as shown in FIG. 13, to thedesired length.

The small end of the workpiece 22 is closed with a seal 58 as is morefully explained below. The large end of the workpiece is brought to bearagainst a fixture plate 59 in fluid sealing relationship therewith,there being a hydraulic pump 60 connected to an inlet line 61 to bringfluid into the interior of the workpiece, and a venting line 62 leadingthrough a valve 63 for purging air and for insuring that the workpieceis completely filled with hydraulic fluid. Thereafter, the valve 63 isselectively closed so as to raise the internal pressure derived from thepump 60 inside the enlarged end so as to cause it to yield tosubstantially the formation shown at the right end of FIG. 14.

The workpiece is removed from the fixture, the large end is annealed,and the operation is repeated as shown in FIG. 15. This step is repeatedfor whatever number of times is necessary to obtain the desiredformation of the enlarged end, a third repetition being illustrated inFIG. 16 and a fourth in FIG. 17, showing the desired final shape. Insomeinstances, the desired shape can be reached in three such formingoperations and in others, it may go as high as five. The pressure usedin the first forming operation typically is on the order of 1,400 psi.In the second forming operation shown in FIG. 15, a typical pressure is1,200 psi. In the third and fourth forming operations, a typicalpressure is 1,000 psi. As the enlarged end grows, its internal areagrows, and therefore progressively less pressure is needed to force theenlarged end to take a shape which is restricted by the flared entrantend of the support 57. The fixture plate 59 is shown ratherschematically, but it includes a collar, not shown, shown schematicallyonly in FIG. 17 at 64, which surrounds the distal end of the workpiece,the portion of the workpiece between the support 57 and the collar 64being open to the atmosphere for visual inspection by the operator as heregulates the valve 63.

The workpiece is longest prior to the first forming operation shown inFIG. 14 and as the material of the workpiece is expanded to have itsdiameter still further increased, the support 57 must move relativelytoward the plate 59 to maintain the seal therewith. Thus, the drawings,in FIGS. 143-47, also illustrate a progressive shift of the support 57.

The seal 58 at the small end is held by a partially extended fluidactuator 65 against the workpiece, the actuator receiving fluid pressurefrom a pump 66 under the control of a valve 67. A constant supportingforce is thereby provided which shifts the support 57 and provides aforce necessary for maintaining fluid tightness at the ends of theworkpiece, thus also compensating for the decrease in length of theworkpiece.

The workpiece 22 is then removed and is trimmed to the form shown inFIG. 18. The enlarged end of the workpiece 22 is then annealed, and itsperiphery is folded out as by means of a press so that it takes the formshown in FIG. 19. The finishing thereafter includes the conventionalformation of a head 68 and a bend 69 in accordance with knowntechnology.

The conventional step of deburring after trimming has been mentionedabove in certain specific instances. Deburring is ordinarilyaccomplished after each trimming operation, as is known. The step ofannealing has been mentioned in several places in the foregoingspecification and has referred to one end, the other end, the tip, orthe entire workpiece, depending upon what the next operation is to be.In some instances herein described, annealing can be omitted where thepart is sufficiently soft to permit the next operation to take place.After certain annealing, it becomes necessary to remove scale bypickling after which the article is dried, as is known. Moreover, theworkpiece is soaped before being subjected to various ones of thedrawing operations, as is known.

In the example given, more than 50% of the metal of the original blank22 is discarded as scrap, and it is therefore known that some of thedescribed steps can be combined as a consequence of routineexperimentation to idealize tooling sizes.

While three mandrels 33, 3'7 and 40 have been disclosed, this numbercould be reduced, particularly if some of the dies were combined ascompound dies. While two forming mandrels 50, 55 have been disclosed,this number could be increased along with an increase in the number ofsteel washers used to lessen the number of ring dies used for decreasingdiameter.

The term uniform wall thickness" as applied to the initial blank issubject, of course, to a mill tolerance of at least $0.002 inch. Theterm uniform thickness" as applied to the bell section is subject tomanufacturing tolerances on the order $0.002 inch, and disregards anythinning of the flare that sometimes occurs during spinning thereof, oneof the finishing operations between FIGS. I9 and 20.

Although various minor modifications might be suggested by those versedin the art, it should be understood that I wish to embody within thescope of the patent warranted hereon, all such embodiments as reasonablyand properly come within the scope of my contribution to the art.

I claim as my invention:

1. A method for making a seamless tubular bell section of a musicalinstrument of sollid brass, comprising:

a. providing a blank of brass, tubing of uniform wall thickness anddiameter;

b. drawing the blank to progressively taper its wall thickness along itslength while maintaining the uniformity of its outside diameter;

c. by drawing, enlarging the end portion of the blank having the greaterwall thickness;

d. by drawing, progressively reducing the diameter of the non-enlargedportion of the blank to provide ultimately a taper in the insidediameter which merges with the enlarged end portion;

e. while externally supporting the blank along its portion of tapereddiameter, by means of hydraulic pressure, expanding the unsupportedenlarged end portion; and

f. trimming and finishing the blank as a bell section.

2. A method according to claim 1 including the step of externallysupporting the non-enlarged portion of the blank during the enlarging ofthe end portion by drawing.

3. A method according to claim 1, including the step of internallyguide-supporting the non-enlarged portion of the blank during theprogressive reduction of its diameter.

4. A method according to claim 1 in which the first drawing is performedin two steps.

5. A method according to claim 1 in which the first drawing is done bypassing the blank with a tapered mandrel therein through a die.

6. A method according to claim 1 in which the enlarging of the endportion is performed in two steps.

7. A method according to claim I in which the enlarging of the endportion is performed by forcing a cylindrical expansion mandrel, havinga tapered entrant end, therein.

8. A method according to claim 3 in which the reducing of thenon-enlarged portion is partially performed by passing the blank with aradially loose guide member therein through a die.

9. A method according to claim 8 in which the reducing of claim 10 isperformed in more than two progressive steps.

10. A method according to claim 3 in which the reducing of thenon-enlarged portion is partially performed by passing the blank with atapered sizing mandrel therein through a steel-washer type of deformingdie.

11. A method according to claim 10 in which the reducing of claim 12 isperformed in two steps.

12. A method according to claim 1 in which the hydraulic expansion isperformed in more than two progressive steps.

13. A method according to claim 12 in which successively lower hydraulicpressures are used to create and to lmiti the amount of expansion perstep.

14. A method according to claim 1 in which the hydraulic pressure isadmitted through one end of the blank and the other end is closed with aseal, including the step of advancing the seal and external support tocompensate for decrease in length caused by the diametral expansion ofthe enlarged end portion.

15. A method according to claim 14 in which the advancing is effected byapplying a constant axial force to the seal and external support as itmoves with the small end of the blank.

16. A method for making a seamless tubular bell section of a musicalinstrument of solid brass, comprising:

a. forming a blank of solid tubular brass to provide an elongatedportion of lesser diameter and a shorter portion of larger diameter,interconnected by an intermediate portion of tapered diameter;

b. while externally supporting the blank along its portion of tapereddiameter, by means of hydraulic pressure, expanding the unsupportedenlarged end portion; and

c. trimming and finishing the blank as a bell section.

1. A method for making a seamless tubular bell section of a musicalinstrument of sollid brass, comprising: a. providing a blank of bRass,tubing of uniform wall thickness and diameter; b. drawing the blank toprogressively taper its wall thickness along its length whilemaintaining the uniformity of its outside diameter; c. by drawing,enlarging the end portion of the blank having the greater wallthickness; d. by drawing, progressively reducing the diameter of thenonenlarged portion of the blank to provide ultimately a taper in theinside diameter which merges with the enlarged end portion; e. whileexternally supporting the blank along its portion of tapered diameter,by means of hydraulic pressure, expanding the unsupported enlarged endportion; and f. trimming and finishing the blank as a bell section.
 2. Amethod according to claim 1 including the step of externally supportingthe non-enlarged portion of the blank during the enlarging of the endportion by drawing.
 3. A method according to claim 1, including the stepof internally guide-supporting the non-enlarged portion of the blankduring the progressive reduction of its diameter.
 4. A method accordingto claim 1 in which the first drawing is performed in two steps.
 5. Amethod according to claim 1 in which the first drawing is done bypassing the blank with a tapered mandrel therein through a die.
 6. Amethod according to claim 1 in which the enlarging of the end portion isperformed in two steps.
 7. A method according to claim 1 in which theenlarging of the end portion is performed by forcing a cylindricalexpansion mandrel, having a tapered entrant end, therein.
 8. A methodaccording to claim 3 in which the reducing of the non-enlarged portionis partially performed by passing the blank with a radially loose guidemember therein through a die.
 9. A method according to claim 8 in whichthe reducing of claim 10 is performed in more than two progressivesteps.
 10. A method according to claim 3 in which the reducing of thenon-enlarged portion is partially performed by passing the blank with atapered sizing mandrel therein through a steel-washer type of deformingdie.
 11. A method according to claim 10 in which the reducing of claim12 is performed in two steps.
 12. A method according to claim 1 in whichthe hydraulic expansion is performed in more than two progressive steps.13. A method according to claim 12 in which successively lower hydraulicpressures are used to create and to lmiti the amount of expansion perstep.
 14. A method according to claim 1 in which the hydraulic pressureis admitted through one end of the blank and the other end is closedwith a seal, including the step of advancing the seal and externalsupport to compensate for decrease in length caused by the diametralexpansion of the enlarged end portion.
 15. A method according to claim14 in which the advancing is effected by applying a constant axial forceto the seal and external support as it moves with the small end of theblank.
 16. A method for making a seamless tubular bell section of amusical instrument of solid brass, comprising: a. forming a blank ofsolid tubular brass to provide an elongated portion of lesser diameterand a shorter portion of larger diameter, interconnected by anintermediate portion of tapered diameter; b. while externally supportingthe blank along its portion of tapered diameter, by means of hydraulicpressure, expanding the unsupported enlarged end portion; and c.trimming and finishing the blank as a bell section.